1. Field of the Invention
The present invention relates to a hydrodynamic coupling device such as a hydrodynamic torque converter including a housing arrangement and a turbine wheel rotatable in the housing arrangement about an axis of rotation and having a turbine wheel shell with a plurality of turbine wheel blades in its radially outer region, is coupled to a turbine wheel hub in its radially inner region, and having a connecting portion connecting the radially outer region of the turbine wheel shell to the radially inner region of the turbine wheel shell.
2. Description of the Related Art
A hydrodynamic coupling device of having a turbine wheel with a radially outer region and a radially inner region with a connecting portion connecting the radially outer region and the radially inner region is known from EP 0 070 662 A1. The turbine wheel shell in hydrodynamic coupling devices of this type is generally produced as a sheet-metal molding and is contoured in a forming operation such that the turbine shell is adapted to various spatial conditions of the coupling device. In coupling devices in which the working-fluid flow circuit is relatively far removed from the axis of rotation, a relatively large radial region is bridged by the connecting portion of the turbine wheel shell. Axial forces generated in the fluid circuit induce a deformation of the turbine wheel shell in the large radial region of the connecting portion with the result that the turbine wheel moves axially away from the opposite pump wheel (and a guide wheel if the coupling device is a torque converter) and may thus cause disturbance in the flow circuit.
To counteract this problem, it is known to produce the turbine wheel shell with a material thickness such that even the axial shearing forces occurring during operation do not lead to excessive deformation. However, this not only has the disadvantage that more material has to be used and thicker material has to be deformed, but also the further considerable disadvantage that a markedly higher mass moment of inertia is acquired, this having an adverse effect on the overall operation of a device of this type.
The object of the present invention is to provide a hydrodynamic coupling device in which deformation of the turbine wheel due to axial shearing forces introduced during rotary operation can be avoided without adversely affecting the overall operation even though the turbine wheel has a large form of construction in the radial direction.
According to the present invention, the object is achieved by a hydrodynamic coupling device including a housing arrangement and a turbine wheel rotatable in the housing arrangement about an axis of rotation. The turbine wheel has a turbine wheel shell which carries a plurality of turbine wheel blades in its radially outer region and is coupled to a turbine wheel hub in its radially inner region. Furthermore, the turbine wheel shell has a connecting portion connecting the radially outer region to the radially inner region.
According to the present invention, the turbine wheel shell also includes a reinforcing arrangement provided in its connecting portion.
In the hydrodynamic coupling device according to the present invention, measures are taken to increase the rigidity of the turbine wheel in that region of the turbine wheel which is critical with regard to deformation when axial shearing forces are generated. Since other radial regions such as the region in which the turbine wheel shell carries the turbine wheel blades are not appreciably influenced by these measures, the operating characteristics of a coupling device of this type remains essentially uninfluenced by the provision of the reinforcing arrangement. That is, the turbine wheel shell which is generally produced as a sheet-metal molding may be manufactured with relatively thin sheet-metal material. The region in which the turbine wheel shell carries the turbine wheel blades is already reinforced by the fixed coupling of the turbine shell to the blades. The region in which the turbine wheel shell bridges a relatively large radial clearance is additionally protected against undesirable deformation by the provision of the reinforcing arrangement.
For example, the reinforcing arrangement may comprise at least one reinforcing element which is fixedly connected to the turbine wheel shell at at least two different radial regions. This fixed connection may, for example, be a welded connection.
At least one reinforcing element does not contact, at least in regions, the connecting portion of the turbine wheel shell between a radially outer connecting region and a radially inner connecting region so that the reinforcing effect introduced by the reinforcing arrangement according to the present invention or the at least one reinforcing element may be provided as efficiently as possible. A hollow reinforcing structure is thus ultimately provided which can efficiently counteract the deformation forces occurring during rotary operation.
A structure of this type may be obtained by the turbine wheel shell extending away from the at least one reinforcing element in the region of the radially inner connecting region and/or radially outside the latter and extending toward the at least one reinforcing element in the region of the radially outer connecting region and/or radially inside the latter.
A configuration of this type may be provided by the turbine wheel shell being produced with an essentially U-shaped or V-shaped curvature profile between the radially outer connecting region and the radially inner connecting region. In addition to the increased rigidity in the axial direction introduced by the connecting arrangement according to the invention, a reinforcing effect in the radial direction may be obtained by the at least one reinforcing element extending essentially rectilinearly between a radially outer connecting region and a radially inner connecting region with the turbine wheel shell.
A bridging clutch arrangement is optionally provided in the hydrodynamic coupling device according to the present invention for selectively making a torque transmission connection between the housing arrangement and the turbine wheel. The bridging clutch arrangement may have a clutch element coupled to the turbine wheel via a torsional vibration damper. The torsional vibration damper has a driving arrangement which is in rotary driving engagement with a counterdriving arrangement provided on the turbine wheel. This counterdriving arrangement is produced on the at least one reinforcing element.
In this further embodiment, the at least one reinforcing element assumes the further function of making a rotationally fixed connection between the turbine wheel and the torsional vibration damper in addition to its reinforcing effect. According to this further embodiment of a hydrodynamic coupling device, no additional components are required for the desired reinforcing effect, since the reinforcing element used may ultimately be that structural part which makes the rotationally fixed coupling between the torsional vibration damper and the turbine wheel.
In this context, the counterdriving arrangement on the reinforcing element may be a plurality of counterdriving projections produced on the reinforcing element.
The reinforcing element may be an annular reinforcing element having a radially inner connecting region connected continuously in the circumferential direction to the turbine wheel shell and a radially outer connecting region connected continuously in the circumferential direction to the turbine wheel shell to obtain as efficient a reinforcement as possible with a simple structure.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.